If you rule out PID, then next condition you should look for is if your chronic pelvic pain worsens during your menstrual cycle and often becomes so severe it affects your daily life. If so, then endometriosis could be the reason.
Endometriosis is a condition where the cells similar to those making up the womb lining move outside the uterus. The condition, while it sounds horrific, is quite common. Endometriosis causes debilitating menstrual pain, as well as pain between periods, bleeding in the middle of your cycle, difficulties with getting pregnant, and painful sex.
Unfortunately, endometriosis can take multiple visits to the gynecologist to be diagnosed, so if you think you have this common cause of feminine pelvic pain, insist on getting tested for it.